1. Field of the Invention
The present invention pertains to a carbonated protein beverage, and to methods of making the beverage.
2. Brief Description of the Background Art
This section describes background subject matter related to the disclosed embodiments of the present invention. There is no intention, either express or implied, that the background art discussed in this section legally constitutes prior art.
Carbonated dairy products have been highly sought after, and several different kinds of product have been developed. One of the more serious obstacles to be overcome is production of a highly carbonated drink (where the carbonation accounts for at least half of the volume of the product) without incurring separation out or precipitation of the dairy protein from the liquid during manufacture and handling, shipping and storage. In addition to manufacturability and shelf life, the taste of the carbonated dairy product has been affected by the kind of proteins present in combination with the carbonation.
Whey protein is a protein fraction obtained from the milk of cows. Milk contains two major protein fractions, including casein, which provides about 80% by weight of the total protein, and whey protein, which provides about 20% by weight of the total protein. Whey protein includes several protein fractions, including, for example, β-lactoglobulin, α-lactoglobulin, Lactalbumin, immunoglobulins (such as IgG1, IgG2, IgA, and IgM, for example), lactoferrin, glycomacropeptides, and lactoperoxidase. Whey protein is more soluble than casein and also has a higher biological value and/or protein digestibility corrected amino acid score (PDCAAS). Whey protein is a rich source of branched chain amino acids (BCAAs), containing the highest known levels of any natural food source. BCAAs are important for athletes, since, unlike the other essential amino acids, they are metabolized directly into muscle tissue and are the first amino acids used during periods of exercise and resistance training. Leucine is important for athletes as it plays a key role in muscle protein synthesis and lean muscle support and growth. Research has shown that individuals who exercise benefit from diets high in leucine and have more lean muscle tissue and less body fat than individuals whose diet contains lower levels of leucine. Whey protein isolate has approximately 45% by weight more leucine than soy protein isolate. Whey protein is available as whey protein concentrate, which may be selected to contain whey protein at a given concentration which may range from about 20% by weight to about 85% by weight protein. Whey protein isolate contains 90% by weight or more whey protein, and little, if any, fat cholesterol, or carbohydrates (e.g., lactose).
Whey protein contains all of the essential amino acids, and therefore, is a high quality, complete source of protein, where complete means that whey protein contains all the essential amino acids for growth of body tissues. Since whey protein is available in forms containing little fat and carbohydrates, it can be a particularly valuable source of nutrition for athletes and for individuals with special medical needs (e.g., lactose intolerant individuals), and can be a valuable component of a diet program. Further, since whey protein contains biologically active proteins such as the immunoglobulins, lactoperoxidase, and lactoferrin, this provides advantages over other protein sources such as soy protein. Whey protein also has a fresh, neutral taste and, therefore, can be included in other foods without adversely affecting the taste.
Given the advantages of whey protein, it has become a popular source of nutrition in the form of whey protein supplemented candy bars and in whey protein powders, available from Next Proteins International, Carlsbad Calif.; a description of these nutritional items is available at the Next Proteins International website on www.nextproteins.com.
In an effort to increase the availability and use of whey protein, efforts have been made to include whey protein drinks among currently available dairy protein drinks. In particular, efforts have been made to include whey protein as a protein source in carbonated beverages. Unfortunately, the carbonation process generally results in destabilization of whey protein, resulting in foaming and/or gelling problems. As a result, the amount of whey protein that has been included in carbonated beverages has been severely limited.
An article by V. H. Holsinger in Adv. Exp. Med. Biol. 1978; 105:735–47, titled: “Fortification of soft drinks with protein from cottage cheese whey”, describes preparation of cottage cheese whey protein concentrates which have the solubility, stability, and flavor to make them suitable for fortification of soft drinks and related products. Carbonated beverages prepared with conventional beverage ingredients and containing up to 1% by weight of the total beverage of added whey protein are said to have maintained clarity, color, and flavor during 203 days of storage at room temperature. Clarity of 1% protein solutions at a pH of 2–3.4 is said to be unimpaired by heating for 6 hours at 80 degrees (without specifying ° C. or ° F.), but some structural change was said to have occurred, since an average of 37% of the protein is said to have precipitated on shifting the pH to 4.7.
Clouding or creaming agents useful for still or carbonated beverages, especially acid types are described in U.S. Pat. No. 4,790,998, issued to Marsha Schwartz on Dec. 13, 1988, and entitled “Beverage Cloud Based On A Whey Protein-Stabilized Lipid”. The composition of matter described comprises a whey protein-stabilized lipid emulsified in an acidic aqueous solution. The important features of the invention are said to include the balancing of the lipid system and the use of whey protein at pH levels of less than 4.5 to achieve acid emulsification stability. All ingredients are said to be natural, i.e., unmodified from the form typically found in nature.
U.S. Pat. No. 4,804,552 to Ahmed et al., issued Feb. 14, 1989, describes a method of carbonating a liquid dairy product to a level of “at least” 1.5 volumes of carbon dioxide dissolved in 1.0 volume of liquid dairy product, while not destabilizing the liquid dairy product. The liquid dairy product is heated to a temperature of at least 160° F. for a time not in excess of 30 minutes, followed by cooling to a temperature of less than about 50° F. The cooled liquid is then subjected to pressurized carbon dioxide to carbonate the dairy product to provide taste and mouth feel. The product is then packaged in closed containers capable of substantially retaining the degree of carbonation. The carbonated dairy product is said to be buffered to a pH of at least 4.0 while being highly carbonated but not destabilized.
U.S. Pat. No. 6,403,129, to Clark et al., issued Jun. 11, 2002, and entitled: “Carbonated Fortified Milk-Based Beverage And Method Of Making Carbonated Fortified Milk-Based Beverage For The Supplementation Of Essential Nutrients In The Human Diet”, discloses dairy or non-dairy based fortified carbonated beverage solutions that supply nutrients in the human diet. The beverage described is said to have carbonation to enhance taste, improve body and mouth-feel and aid in the stabilization of milk protein such as Lactalbumin and Casein.
Published patent application US 2002/0127317 A1 of Hotchkiss et al., published Sep. 12, 2002, describes processes to inhibit or reduce the growth of bacteria and other pathogens in a liquid by adding carbon dioxide to the liquid, and thermally inactivating the bacteria and other pathogens. The process is said to be applicable to a wide variety of fluids, liquids, semi-solids and solids. Prior to or simultaneously with thermal inactivation carbon dioxide (CO2) is added to the product by sparging or bubbling, preferably to obtain levels of about 400–2000 ppm. At this level of CO2, the amount of microbial death that occurs during heating in a normal pasteurization (HTST) process is said to be increased by 10% to 90% over thermal inactivation carried out without the addition of CO2 prior to the thermal inactivation step. After completion of the thermal inactivation process, the free CO2 is said to be removed.
U.S. Pat. No. 6,761,920 to Jeffrey Kaplan, issued Jul. 13, 2004, and entitled: “Process For Making Shelf-Stable Carbonated Milk Beverage”, describes an aerated or carbonated milk product drink made using a method which includes pre-heating, pressurized ultra-heat treating, subsequent carbonation with a gas or gases under pressure, and packaging into a container. The method of producing the shelf-stable carbonated milk product comprises injecting under pressure carbon dioxide gas or a mixture of gases into the milk product at low temperature of less than 10 degrees centigrade and high pressure of from 50 kpa to 200 kpa. In a typical process, as illustrated in FIG. 1, the milk product is pre-heat treated at a temperature of 80° C. to 138° C., followed by ultra-heat treatment from about 138° C. to about 150° C. in a holding tank, where it is held at a pressure of 700 KPA or an appropriate pressure. The carbonation may be achieved by direct injection of sterilized, purified carbon dioxide gas in a holding receptacle, or may be injected in line. Preferably the carbonation process is carried out at 2° C.±1° C. Then the carbonated liquid is transferred to a holding tank, where it is maintained at a pressure of 450 KPA and a temperature of 2° C. to 6° C. If, for some reason, the amount of carbonation of the pre-heated ultra heat treated milk product is insufficient, the product may be diverted to be reprocessed through the carbonater in a return loop to a holding tank to be re-pasteurized to be within the specification. After carbonation, the product is conveyed to a packaging station for packaging into sterile containers. The pH of the product is said to be preferentially maintained at 4.0 to 5.7 during packaging operations, depending on the product. After packaging the milk product into individual containers, it is said that the milk may be further sterilized by non-toxic radiation or pasteurization, however no enabling description of how this would be done is provided.
U.S. Pat. No. 6,866,877 to Clark et al., issued Mar. 15, 2005, entitled: “Carbonated Fortified Milk-Based Beverage And Method For Suppressing Bacterial Growth In The Beverage”, describes dairy or non-dairy based fortified carbonated beverage solutions that supply essential nutrients in the human diet. In addition to describing the composition of a beverage, the patent discloses a method of using carbonization to reduce bacterial counts and reduce degradation of essential nutrients in milk-based beverages with or without pasteurization. In one embodiment, CO2 is added pre-pasteurization to eliminate or effectively reduce the growth of bacterial colonies in the beverage and reduce degradation of nutrients if UHT pasteurization is used. If CO2 is added pre-pasteurization, it is said that CO2 must be reintroduced, since pasteurization disseminates most CO2 present. This is done by in-line addition of CO2 after the beverage's temperature is brought down from about 185° F.–215° F. to about 40° F. The CO2 concentration in the final product is preferably from about 500 ppm to about 3,000 ppm. 1,000 ppm is said to be about 0.5 volumes of carbonation per volume of liquid beverage solution, so that the final product contains about 0.25 volumes to about 1.5 volumes of carbon dioxide per volume of liquid beverage solution.
As is illustrated above, there are a number of different factors which need to be considered in development of a carbonated protein drink. Some of the references appear to teach away from each other in terms of concentrations of protein which can be used in a carbonated protein drink, amount of carbonation which can be used (and still enable a shelf-stable beverage), and pH at which various protein-containing carbonated beverages are shelf-stable.
There is also considerable lack of detail in the processing method steps described, to the extent that one of skill in the art would not be enabled to produce a carbonated protein drink after minimal experimentation, in view of the description. Inactivation of microbes after carbonation of the beverage appears to be a problem, requiring subsequent “recarbonation” to ensure that the beverage has the proper taste and mouth feel.
The carbonated protein drink composition of the present invention, produced using the method described below, provides a high protein content (relative to previously described carbonated drinks) where the amount of carbonation is also high. In addition, while the carbonated protein drink has been heat treated to inactivate microbes, the final product exhibits storage shelf-stability which is unexpected for such a product.